The present invention relates to an inkjet-recording non-aqueous ink composition, an inkjet recording method, and a recorded matter.
A commercially-available aluminum pigment has an average particle diameter of 10 micrometers or more (see U.S. Pat. Nos. 4,233,195, and 5,662,738, for example). Therefore, it is very difficult to cause the aluminum pigment to pass through a minute nozzle (diameter: 30 micrometers or less) of an inkjet printer or a filter. When the average particle diameter of the aluminum pigment is reduced, the aluminum pigment reacts with water due to an increase in surface area. It is very difficult to obtain an aluminum pigment having an average particle diameter of 1 micrometer or less using a grinding method or an atomization method. In order to solve such a problem, a tabular aluminum pigment which can be used for an inkjet ink has been proposed (see JP-A-2007-131741, for example).
The viscosity of an inkjet-recording ink composition must be adjusted to an appropriate level in order to discharge a constant amount of ink onto a recording medium. When using a non-aqueous ink composition, an organic solvent having a high viscosity, a resin, or an emulsion in which a resin is dispersed is normally added to the ink composition as a viscosity controller. However, when adding an organic solvent having a high viscosity to a non-aqueous ink composition containing a metallic pigment, a considerable period of time is required for the ink to be dried on a recording medium. Moreover, the ink fixation capability deteriorates. When adding a resin or an emulsion in which a resin is dispersed to an ink composition containing a metallic pigment, the metallic glossiness and the ink discharge stability deteriorate.
When printing an image on a printing medium using an inkjet printer by utilizing a tabular aluminum pigment, since the orientation of the pigment during and after drying of the ink changes depending on the printing environment, the original glossiness of the ink may not be obtained depending on the printing environment. As a result, the printing area may not exhibit sufficient glossiness.